Effect of MgO nanolayer coated on Li3V2(PO4)3/C cathode material for lithium-ion battery

MgO nanolayer coated on Li3V2(PO4)3/C particles was successfully prepared by a sol–gel method. The X-ray diffraction (XRD) shows that the crystal structure of the Li3V2(PO4)3/C cores does not been affected by the coating. Nanolayer-structured MgO on the surface of Li3V2(PO4)3/C particles is demonstrated by high resolution transmission electron microscopy (HRTEM). Galvanostatic charge/discharge, EIS and cyclic voltammetry measurements clearly show that MgO nanocoating stabilizes the structure of the cathode material, decreases the interface charge transfer resistance and enhances the reversibility of electrode reaction. Electrochemical properties of the coated samples were investigated, showing enhancements of the initial discharge capacity, the cyclability and the rate performance. For MgO of 4.5 mol% coated sample, the initial discharge capacity is 194.4 mAh g−1 at 40 mA g−1 current density, which is close to the theoretical discharge capacity of 197 mAh g−1, and the discharge capacity remains 137.5 mAh g−1 after 100 cycles, and its capacity retention of 70.73% is higher than that of pristine Li3V2(PO4)3/C, 43.7%. The initial discharge capacity still reaches 157.81 mAh g−1, 157.29 mAh g−1 and 144.64 mAh g−1 at 1C, 1.5C, 2C rates, respectively.